In typical multiple component applicator devices, component materials are stored separate from one another and are dispensed concurrently with one another such that the correct ratio of component materials for a proper mixture are provided. The component materials may be mixed within such applicator devices, or may be mixed externally after the proper proportional amounts are dispensed.
Generally, many types of adhesives, sealants, coatings and potting compounds may comprise multiple components. Such adhesives may include components including epoxies, urethanes, acrylics, polysulfides, polyesters, silicones, and any other known or discovered adhesive or sealant materials.
Epoxy adhesives are representative of such multiple component adhesives, and more generally of multiple component products, which require that the component materials be stored individually and which must be mixed in accordance with a specific ratio for usage. Epoxy adhesives typically include an epoxy resin component and a curing agent component such that when mixed together in proper proportion, the epoxy curative hardens in place. With this in mind, epoxy adhesive dispensing devices have been developed which include separate storage locations for the resin component and the curing agent component and a means for dispensing the separate components together and in accordance with the proper ratio for curing.
One manner of concurrently dispensing separate component materials is to provide the component materials within distinct cavities or barrels of an applicator device and to force the component materials from such cavities or barrels by actuation of a single element. Examples of dispensers including plural barrels which each contain a component material which is expelled by a plunger inserted within each barrel, and wherein the plungers are driven together by the manipulation of a single element are disclosed in U.S. Pat. Nos. 4,471,888 to Herb et al, 3,952,920 to Bergman, and 2,826,339 to Maillard, and in German Offenlegungsschrift 2,335,601. In each of these cases, the manipulation of either a trigger, a lead screw mechanism, or a plunger element directly results in the concurrent and equal movement of each plunger such that component material is expelled from plural cavities or barrels. One common disadvantage associated with each of the above devices is that such dispensers lack overall versatility, and they are not easily changed to accommodate different ratios for different component materials. In other words, the devices are substantially set at the manufacture thereof to dispense the component materials at preset ratios.
A somewhat more versatile dispenser is described in U.S. Pat. No. 3,828,980 to Creighton et al, in that the device includes a like number of pistons as there are component material holding barrels, wherein the pistons are separable from one another but are actuatable together by a separable rigid connecting means. However, the Creighton et al device is disadvantageous for the same reason as the above-described devices in that the multiple component barrels are formed as a single cartridge which is divided into compartments which are non-divisible from one another. Thus, the dispenser, whether having two or more component barrels, is limited in use to producing a mixture of that number of components as there are fixed barrels and at the predetermined ratio thereof.
Schroeder, U.S. Pat. No. 4,260,077, discloses yet a more versatile dispenser, wherein the dispenser comprises not only separable plungers, but also separable barrels. The barrels are detachably connected together by a sliding interlock, and the plungers are moved concurrently by inter-fitted elements. The principle advantage of the Schroeder device is that each one of the barrel and plunger assemblies is usable independently of the other. Moreover the dispenser is particularly directed to a dispenser which can equally dispense component material from two barrels and can be separated for individual use of each barrel and plunger assembly. Because of the need for each separable barrel and plunger assembly to be independently usable, each assembly necessarily includes all of the necessary operable component parts, including nozzles. Thus, even when connected together and dispensing two component materials together, the component materials are expelled through individual discharge openings, and the component materials must then be mixed together externally of the dispenser by other means.
A significantly advanced two component applicator assembly has been developed with increased two component versatility and is available as the "Scotch-Weld.TM. EPX Applicator System" from Minnesota Mining and Manufacturing Company of St. Paul, Minn., the assignee of the present invention. The "Scotch-Weld.TM. EPX Applicator System" comprises an applicator and plunger assembly to which a removable fixed two component barrel assembly is detachably connected. The barrel assembly further includes a separable static mixing nozzle connecting to the discharge openings of both components. Many varieties of two component room temperature curing products are available prepackaged within the removable barrel assemblies from Minnesota Mining and Manufacturing Company under the product line "Scotch-Weld Duo-Pak" adhesive cartridges. Thus, a user of the applicator can purchase any one of the available adhesives and simply attach the barrel assembly to the applicator and plunger assembly for dispensing. The individual prepackaged barrel assemblies for specific adhesives are designed in accordance with a predetermined mix ratio for that specific adhesive. Thus, a single applicator and plunger assembly can dispense any one of the variety of available two component adhesives at the predetermined ratio depending on the specific adhesive and use thereof.
A further variation has been developed and is available as the "RATIO-PAK.TM. Cartridge System" from Plus-Pak Industries, Inc., of Niantic, Conn. This system includes a removable cartridge system, like the "Scotch-Weld".TM. System, where the cartridge system consists of two separable cartridges (barrels). Different cartridge sizes are available so that they can be configured to dispense components at selected mix ratios, specifically within the range of 1:1 to 10:1.
The "Scotch-Weld.TM. EPX Applicator System" and all other two component applicator devices suffer from a common problem which occurs when a third component, or more, is attempted to be added to the two components which is not compatible or stable with the other two components. Moreover, even if a third component is compatible or stable with at least one of the other two components, such two component devices lack the versatility to be able to selectively add such a third component to the other two components only when desired. For example, one may wish to add a third component during only a portion of the application of a two component adhesive. Examples of components not compatible or stable would include materials which react with the base material or anything of higher density than the base material, such as flame retardants, glass beads, conductive metal, thermally conductive fillers, and the like, where such higher density materials would tend to settle within the tubes during storage before use. In the same manner, lower density additives would tend to float within the base material destroying a uniform mixture.
Applicator devices including the capability of dispensing three or more components are also known. The aforementioned U.S. Pat. No. 2,826,339 to Maillard discloses in one embodiment a three component dispenser having three coaxial compartments from which the components are concurrently dispensed. Such a device, however, is no more versatile than a fixed two component device in that it is limited in use to component materials of a like number as there are fixed compartments.
Another three component dispenser is described in U.S. Pat. No. 4,995,540 to Colin et al, wherein a typical two barrel dispenser is provided with two separated component materials within one barrel and with a single component material within the other barrel. Thus, the separated component materials of the one barrel are sequentially dispensed and mixed with the single component material of the other barrel. This device does not permit dispensing of three or more components concurrently.
Falco, U.S. Pat. No. 4,913,553, discloses a multi-component dispensing apparatus having more than two component barrels, but which is limited to the provision of a pair of dispensing barrels for each component material to be dispensed. In other words, the device, in accordance with that invention, must have an even number of component barrels which are equally distributed about the drive axis of the device for balancing the device during application. It is suggested that more than two component materials can be dispensed if the additional components are provided by a pair of additional component barrels balanced about the drive axis. This device, like those described above is limited in use for applying and dispensing component materials of a specific number for which the applicator apparatus is specifically designed.